The present invention relates in general to catheters useful in the diagnosis and/or treatment of coronary diseases or conditions. More specifically, the present invention relates to coronary catheters for use in the diagnosis and/or treatment of diseases or conditions in the right coronary artery.
Diagnosis and/or treatment of coronary artery diseases or conditions typically involves the insertion of a catheter through the vascular system of a patient and to the proximity of the site which is being treated or examined. For example, in coronary angiography or arteriography, a hollow catheter is typically inserted into an artery, such as the femoral artery in the patient's leg, and guided by a guide wire or guiding catheter upwardly through the descending aorta, over the aortic arch and downwardly into the ascending aorta. The tip of the catheter is then inserted into the ostium of either the right or the left coronary artery, depending on which specific artery is to be examined. After the tip of the catheter is inserted into the ostium, radiopaque liquid is injected through the catheter to provide an x-ray image of the condition of the particular artery and thus aid in the diagnosis of any coronary artery condition or disease present.
Development of a catheter for use in the diagnosis and/or treatment of coronary diseases or conditions involves application of various and sometimes competing considerations. There are, for example, physiological considerations in the design of coronary catheters. The openings into the left and right coronary arteries are not symmetrical. If the ascending aorta is viewed in cross-section and from below, the ostium for the right coronary artery is located generally at an eleven o'clock position and the ostium for the left coronary artery is located at approximately the three o'clock position. Because of this asymmetry, catheters have been designed with different tip shapes peculiar to whether the procedure is to be carried out for the right or left coronary arteries. Dr. Melvin Judkins described particular catheter tip configurations for right and left artery procedures many years ago. Catheters having such tip configurations are commonly referred to as "Judkins" catheters.
Because of the central (three o'clock) position of the ostium for the left coronary artery, the so-called "left" Judkins catheter works well, and requires relatively little manipulation by the physician to place the tip end of the catheter into the coronary ostium. The ostium for the right coronary artery, however, is not located in as convenient a position, and the Judkins catheter for the right coronary artery requires that the doctor to rotate the catheter approximately 180.degree. after it is inserted past the ostium and then to withdraw the catheter slightly until the tip enters the right ostium. In a living patient, where the heart is beating and the artery pulsing, placement of the right Judkins catheter can be very difficult, and may require extensive experience before a level of proficiency is attained.
To provide sufficient rigidity for rotation of the catheter to the desired position, right coronary artery catheters typically have a metal braid within the wall of the catheter. The metal braid stiffens the catheter and transmits the torque exerted by the physician when the physician twists the proximal end of the catheter, which is located outside the patient, to rotate the distal end that is located in the ascending aorta.
The drawback with the braided catheter, however, is that the braid results in a catheter having a larger outside diameter. Because doctors prefer the inside diameter of the catheter to be as large as possible for the maximum flow rate of radiopaque liquid (so as to provide the sharpest x-ray image) the provision of a metal braid in the wall of a catheter is typically accommodated by increasing the outside diameter of the catheter.
The larger outside diameter, however, requires a larger incision for entry of the catheter into the patient's artery. Larger incisions, however, require longer times to clot. Increased clotting time may require an overnight stay of the patient in the hospital, resulting in increased cost as compared to procedures carried out on an out-patient basis.
As a result of these competing considerations, there continues to be a need and desire for improved coronary catheters. In particular, there is a continuing need for coronary catheters for diagnosis and treatment of the right coronary artery, which catheters may be readily placed into the right coronary artery ostium but also have minimum wall thickness, thereby allowing for the maximum inside diameter for radiopaque fluid flow and the smallest outside diameter for the minimum incision.
One attempt to provide an alternative coronary catheter for use with the right coronary artery is disclosed in U.S. Pat. No. 4,883,058 to Ruiz. In the Ruiz patent, the distal end of the catheter comprises a relatively sharp curve with a small radius of curvature at the most distal tip portion and a larger curve in the opposite direction upstream of the tip portion. The curvature of the larger curve is not as great as the curvature of the aortic arch, so as to bias the tip portion against the outer wall of the ascending aorta.
Although the '058 Ruiz patent may be a step in the right direction, it also appears to have several shortcomings. Because the tip is biased outwardly, the guidewire must remain in the catheter as it passes upwardly along the descending aorta and over the aortic arch and into the ascending aorta. Otherwise the tip may become caught in the arterial branches in the top of the aortic arch. If the guidewire must remain in the catheter, the catheter cannot be periodically flushed with radiopaque liquid as physicians often desire to do to visualize the location of the catheter tip as it moves through the aorta. The catheter shown in the '058 Ruiz patent also requires the physician to apply a torque to the proximal end of the catheter to cause the catheter tip to rotate somewhat for insertion into the ostium.
Accordingly, it is an object of the present invention to provide a catheter for use unconnected with the right coronary artery which does not suffer from the drawbacks described above.
It is a more specific object of the present invention to provide a catheter for the diagnosis and treatment of diseases or conditions of the right coronary artery which requires minimum manual adjustment or positioning for placement of the tip of the catheter in the right ostium.
It is yet a further object of the present invention to provide a catheter for the right coronary artery which cooperates with the shape of human aortic arch for automatic placement of the catheter tip in the proximity of ostium so that minimum adjustment or manipulation of the catheter is required.